1. Technical Field of the Invention
The present invention relates to optical communication devices, and more particularly enclosures for optical communications devices that provide alignment between the optical communications device and an optical cable.
2. Description of Related Art
An optical interconnect module is an optical-electrical device that enables an interface between optical communications systems and electrical communications systems. One or multiple optical fibers, bundled in an optic cable, are connected to the interconnect module to communicate with optical-electrical components of the interconnect module. The optical-electrical components interface data transmitted on the optical fibers to electrical communication systems or interface electrical communications systems to optical communications systems.
An optical cable may need to be repeatedly connected and disconnected from the optical interconnect module. Because the optical fibers are generally very small, the alignment tolerance required to ensure that the fibers align with their respective optical and optical-electrical components is a few microns or less. The alignment tolerance must be reliably and repeatable achieved each time the optical fiber is reconnected to the optical interconnect module.
Referring to FIG. 1, an optical interconnect module 10 typically has a lid portion 12 and a base portion 14 which form the enclosure. The lid 12 joins with the base 14 to enclose and protect optical and optical-electrical components 22 (eg. an electro-optical transducer) from the exterior surrounding environment. Focusing elements 24 reside on the lid 12 to focus light from each optical fiber onto optical-electrical components 22 or light from the optical-electrical components 22 into an optical fiber. A ferrule 17 on the end of the optical cable 16 secures the optical cable to the lid 12 and aligns the optical fibers with their respective focusing elements 24. Thus, the ferrule 17 must be precisely positioned on the lid 12 so that the optical fibers align with their respective focusing elements 24, and the lid 12 must be precisely aligned with the base 14 so that focusing elements 24 are aligned with their respective optical-electrical components 22.
In one prior art interconnect module 10, guide pins 26 are received in pin retaining receptacles 28 of the base 14. The pin retaining receptacles 28 are positioned in precise relation to the optical-electrical components 22. The lid 12 has corresponding alignment apertures 30 through which pins 26 pass as the lid 12 is placed on base 14. The corresponding alignment apertures 30 are positioned in precise relation to focusing elements 24, so that focusing elements 24 are aligned with the optical-electrical components 22 when the lid 12 is placed on the base 14. The ferrule 17 has alignment receptacles 19 which closely receive the pins 26 to secure and align the optical cable 16 onto the lid 12.
To achieve the high connection tolerances required in the interconnect module 10, the components must each be fabricated with very high precision. Thus, the pins 26 are precision machined to fit closely within the alignment receptacles 19 of the ferrule 17. The retaining receptacles 28 are fabricated in the base 14 in precise relation to the optical-electrical components 22 and precisely spaced to match the spacing of the alignment receptacles 19 of the ferrule 17. The retaining receptacles 28 must also be precision registered with the pins 26. Finally, the alignment apertures 30 are fabricated in the lid 12 and in relation to the focusing elements 24, and then precision registered with the pins 26. This multi-step machining process is costly and time consuming, and is repeatedly performed for each lid and base. Extreme care must be taken to avoid a tolerance stack-up leaving the optical interconnect module out of tolerance.
It is desirable to reduce the time and expense involved in manufacturing optical interconnect modules. Thus, there is a need for lower cost optical interconnect module and a method of manufacturing the same with fewer high precision manufacturing steps.